The invention relates to a method for manufacturing an inflatable closing plug for pipes, which plug comprises a balloon-like element of elastic material.
Such plugs are used for closing pipes, for instance gas pipes, and are inserted beforehand in an opening of the gas pipe, whereafter the balloon-like element is placed under pressure by means of compressed air or the like so that the balloon widens and closes the passage of the pipe. In order that the balloon is able to exert any pressure on the inner wall of the gas pipe, the balloon must have limited freedom of movement, whereby a separate sheath of woven material is arranged round the balloon. This separate sheath has a limited elasticity so that, when the balloon is inflated, it cannot extend in axial sense of the pipe and the pressure of the gaseous medium in the balloon is applied against the inner wall of the pipe so that an adequate closing pressure can be obtained.
Manufacture of a balloon with a separate sheath therearound is quite time-consuming and moreover has the limitation that the variation in diameters of the pipes for closing must be limited, whereby balloons with different nominal working diameters must be used and held in stock.
Plugs are already known wherein the balloon-like element is provided with reinforcement wires in the outer surface thereof, which wires are anchored in end pieces. The manner of manufacturing such a balloon-like element is likewise time-consuming and costly.